1. Field of the Invention
The present invention relates to frame counting method and device in a camera. More particularly, the present invention pertains to a frame counting method and device in a camera which is applied to a camera which records, onto film or in a film cartridge, the data on photographing conditions such as whether the film has any unexposed frames or not.
2. Description of the Related Art
In the case of photographing ordinary 35 mm film, if the photographing for all frames on the film is over, or if the rewinding of the film is directed while the film is being exposed, the rewinding of the film starts automatically.
In the process of rewinding the film, a frame counter displays frame numbers, decreasing the number one by one every time the film is rewound frame by frame. After the leader of the film is wound in a few seconds, the frame counter displays such marks as "E" (representing Empty).
There is proposed a new type of a film cartridge as shown in FIG. 6. This film cartridge 10 has a single spool 12, and film 14 is wound around the spool 12. A perforation 14A is formed on the film 14 to indicate a position of each frame, and a magnetic recording layer 14B is formed on the entire back surface of the film 14 or at the edge of the film 14. Information about each frame can be recorded onto the magnetic recording layer 14B.
The aforementioned film cartridge 10 is able to wind up all unexposed film, film being exposed, undeveloped film, and developed film into the film cartridge 10. Although not shown in FIG. 6, a light-shielding lid is provided at a film slot of the film cartridge 10 so as to prevent the film 14 within the film cartridge 10 from being exposed.
In a camera using the aforementioned film cartridge 10, if the photographing for all frames on the film 14 is over, or if the rewinding of the film 14 is directed while the film 14 is being exposed, the rewinding of the film 14 starts. If the whole film has been rewound into the film cartridge 10, the light-shielding lid of the film cartridge 10 is closed, and the information indicating whether the film 14 has any unexposed frames or not is recorded onto a recognition means provided in the film cartridge 10. Then, the film cartridge 10 can be taken out of the film cartridge chamber of the camera.
For the reasons stated above, as shown in FIG. 7, the time t.sub.2 is required for rewinding the film leader, closing the light-shielding lid, and recording the aforementioned information after the frame counter displays "1" until the frame counter displays "E", and the frame counter displays "---" during the time t.sub.2. Because the time t.sub.2 is a long period of 10 seconds, there is a possibility that a user determines that the rewinding has been completed (the film cartridge is allowed to be taken out) in the time t.sub.2, and that the user may open a film cartridge chamber carelessly to thereby expose the film to the outside light.